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I just finished building the BYOC envelope filter and question whether it is working as intended. I built it stock using all the BYOC delivered kit parts. All the basic functions seem to work as intended (LED, bypass, manual mode, auto mode). My concern is with the sound in auto mode. With longer gaps between stiking chords/notes, it seems to work fine (each time I pick, the filter starts at a lower frequency, rises and then falls giving a wah sound). When picking faster the filter starts at a lower frequency on the first pick, but stays at the higher frequncy on subsequent picks. In other words, I don't get a wah sound on fast picks unless I allow time for the filter to 'cycle' down.

Is this normal? I've tried adjusting the filter but can't seem to get it to restart at the lower frequency with each pick. Have I not found the sweet spot?

I've attached a sound file (WinZip format) to demonstrate. Sorry for the sound quality (some distortion), but I don't have any special recording software and am just using software that came with the PC sound card.

Clean sound 0-15 seconds
Auto mode (slower picking) 16-28 seconds
Auto mode (faster picking) 29-37 seconds

Any comments/help would be appreciated.

This is completely normal.

First, the long version:
http://www.geofex.com/Article_Folders/E ... cftech.htm

Now the short version:
All envelope effects (which also includes most compressors) work by converting your guitar signal to a polarized DC voltage through a process called "rectification" and then using that voltage to affect something else in the circuit. (In an envelope filter, it creates a tone sweep, producing a wah sound.) However, your guitar signal isn't a steady source of voltage. Even our power supply isn't a truly steady source of voltage -- which is why we need filtering caps. A wave goes up AND down across a zero line, but we really want to focus on the TOP of the wave.

A capacitor can be used to store the correct polarity of voltage in between those wave swings. The capacitor discharges at a slow-ish rate, or at any rate much slower than a single swing of a wave. That's called the "decay." It's what keeps the circuit from flubbing out or going "wah wah urrrrg huh? WAHAGAIN! wahhg" and instead going "WOwwwwwwwww" when you hold a note.

The tradeoff is that if you pick really fast the capacitor won't drain fast enough to reset the circuit to its idle state.

Hammer's article gives some clues as to what to look for in the circuit if you're interested in a variable decay.

_________________
I'm Jon. My band. Just me. Vids. PCBs: Bearhug & Cardinal: 1776 Effects. Hamlet & Blue Warbler: JMK PCBs. Flabulanche: Madbean

And by all means, play around with the sensitivity, range and attack controls to dial in the pedal's performance to your particular set-up and playing needs. But there are certainly practical limitations given the nature of how the effect works, as described above.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks for both of your quick replies (midwayfair and duhvoodooman). Since this was my first build, good to know it works as intended.

Is there a way to add a rate (of decay) control. Thinking of something like Mooer Funky Monkey.

Thanks.

Yes, read the "mysteries of envelope detection" part of the article I linked to and compare the envelope detector with the BYOC schematic for the pedal you built (page 26 of the instructions). They're not vastly different.

If you get stuck, ask further questions, but you will learn more by reading the schematic and recognizing patterns.

_________________
I'm Jon. My band. Just me. Vids. PCBs: Bearhug & Cardinal: 1776 Effects. Hamlet & Blue Warbler: JMK PCBs. Flabulanche: Madbean

Ok. I'm sure this would be a lot easier if I were an EE. But here goes. Laughing and snide remarks are allowed if they help lead to the correct answer.

Looking at the BYOC envelope filter schematic I surmise the following:
1. The lower right is the manual circuit (A100k pot and 10k resister)
2. The upper left is the input stage as referenced in the article you referenced.
3. Across the top to the right of the input stage is the filter circuit as referenced in the referenced article. Range pot (B100k) is in the middle of this circuit.
4. The very lower left is the LED circuit.
5. Above the LED circuit and across the middle is the envelope detector stage. The sensitivity pot (C250k) and the attack pot (B100k) are in this circuit. If this is correct, then the 150k resistor (+9v one end - attack pot, 22k resistor and diode on the other end) would control the decay rate and hence the rate. What is confusing is the +9v on the resistor and not a negative voltage to allow the decay.

So what do I understand correctly and what do I not understand? Thanks for any help/direction you can supply.

So I removed the 150k resistor (R21) and substituted a 1M ohm linear taper pot. Set it to 150k ohms to establish that the filter continued to work in the same manner, which it did. I then tried raising and lowering the value for R21 using the pot. I couldn't detect any change in decay time, no matter where I set the pot. Unless the change is extremely subtle, the 150k resistor doesn't impact the decay time. Varying R21 seemed to have a slight effect on the attack time instead.

This is the problem with testing an idea. Many times you end up proving yourself wrong.

Using the schematic pinned in this envelope subforum, I still believe that I have identified the major circuit sections correctly. Top left (IC1) is the input stage (gain). From there the signal splits into 2 paths. Across the top is the filter circuit (IC2). And across the bottom is the detector circuit. IC1 is the sensitivity portion, actually it looks like an attenuator for the gain stage from above. It then goes to the attack section (Q1) before feeding back into the filter. The lower right is the manual switch and pot for the fixed wah sound.

Having said all that, it still looks like R21 should be the resistor to set the decay time.

Still looking for input to my feeble attempt at understanding this circuit. In the mean time, I guess I'll pull R22 and see if it influences attack or decay time. Since R21 seemed to impact attack time, maybe R22 controls the decay time.